Plasma processing method and plasma processing apparatus

Abstract

A plasma processing method according to an aspect includes: preparing a plasma processing apparatus including: a chamber; a lower electrode; an upper electrode; a focus ring surrounding a peripheral edge of the lower electrode; and an annular coil disposed on an upper portion of the upper electrode at a more outer position than the peripheral edge of the lower electrode; placing a substrate on the lower electrode, with a peripheral edge of the substrate surrounded by the focus ring; introducing process gas into the chamber; generating plasma of the process gas by applying high-frequency power across the upper electrode and the lower electrode; and leveling an interface of a plasma sheath on an upper portion of the substrate with that on an upper portion of the focus ring by generating a magnetic field by supplying a current to the annular coil.

What is claimed is: 
     
       1. A plasma processing method comprising:
 preparing a plasma processing apparatus, the plasma processing apparatus comprising:
 a chamber; 
 a lower electrode disposed in the chamber; 
 an upper electrode disposed in the chamber and facing the lower electrode; 
 a focus ring disposed in the chamber and surrounding a peripheral edge of the lower electrode; and 
 a plurality of annular coils disposed on an upper portion of the upper electrode and being concentric with a substrate to be placed on the lower electrode, one of the annular coils being disposed outside the peripheral edge of the lower electrode, the others of the annular coils being disposed inside the peripheral edge of the lower electrode; 
 
 placing the substrate on the lower electrode, with a peripheral edge of the substrate surrounded by the focus ring; 
 introducing process gas into the chamber; 
 applying high-frequency power across the upper electrode and the lower electrode to generate plasma of the process gas; 
 generating a magnetic field by supplying a current only to the one of the annular coils to level an interface of a plasma sheath on an upper portion of the substrate with the interface of the plasma sheath on an upper portion of the focus ring for reducing the occurrence of tilting in a pattern formed on the substrate by etching with the plasma, wherein a horizontal component of the magnetic field generated from the one of the annular coils has the highest value outside the peripheral edge of the substrate; and 
 varying the current to be supplied to the one of the annular coils according to a worn state of the focus ring. 
 
     
     
       2. The plasma processing method according to  claim 1 , wherein the step of supplying a current includes supplying a direct current to the one of the annular coils to generate a magnetic field substantially without electric field.